The proposed research is concerned with developing a set of experimental procedures useful for the investigation of Pavlovian conditioning influences on blood glucose regulatory mechanisms under conditions of 'natural' glucose ingestion. On each of a number of days rats will be placed in a specific experimental environment and, 20 minutes later, presented with glucose solutions for a 6-minute access period. After a number of such conditioning trials the animals will be placed in the apparatus and then removed at different times prior to, at, and after the time glucose would normally have been presented. On this test day a blood sample will be withdrawn from the animals' tails, analyzed for glucose levels, and compared with control rats similarly treated but not given glucose. It is anticipated that a stimulus context regularly associated with carbohydrate ingestion will acquire the properties of eliciting anticipatory regulatory responses which will, in turn, lead to hypoglycemia. Several proposed experiments are designed to provide information concerning the existence of such conditioning influences, the procedures necessary to demonstrate them, the nature and robustness of the conditioning, and some information on the relative contribution of oral and postingestive factors and the mechanisms of neural mediation.